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Derive the equation of the parabola with a focus at (-5, 5) and a directrix of y = -1. (2 points) Please help

2 Answers

6 votes

Answer: f(x)=1/12(x+5)^2+2

User Tommz
by
7.3k points
2 votes
we see that the the parabola opens up since directix is below the focus

for an parabolla opening up/down with vetex at (h,k) and the distance from teh vertex to the focus is p

(x-h)^2=4p(y-k)
the distance from vertex to directex is the same as from focus to directix

from (-5,5) and y=-1
that is a vertical distance of 6
vertex is in the middle
6/2=3
5-3=2
the vertex is at (-5,2)
the distance is 3

(x-(-5))^2=4(3)(y-(2))

(x+5)^2=12(y-2)

y=(1)/(12)(x+5)^2+2

User Grizwako
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6.5k points